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Equine Herpesvirus

What is Equine
Herpesvirus (EHV)?

Equine herpesvirus (EHV) is a family of equine viruses named by numbers including EHV-1, 2, 3, 4 and 5 with EHV-1,3,4 posing the most risk for domestic horses. EHV is a common DNA virus that occurs in horse populations worldwide. The two most common species are EHV1 and EHV-4; both can cause abortion, respiratory disease and neurologic disease.

EHV-1 most often causes a respiratory disease which is usually mild and self-limiting, however, rarely EHV-1 and 4 can cause equine herpesvirus myeloencephalopathy (EHM) a neurologic disease affecting the spinal cord and can be fatal. EHV-3 causes coital exanthema a venereal disease which affect the external genitalia. Horses can be carriers of EHV with no clinical signs and can spread the disease to other horses. Testing and quarantining affected horses in isolation is the primary way to control the disease. Vaccines are available but do not completely prevent any form the disease.


Equine Herpesvirus- Abortion
April 09, 2021
Regional Municipality of York, ON
Confirmed Case(s) - Voluntary Quarantine
Equine Herpesvirus- Neurologic
September 24, 2021
Olmstead County, MN
Confirmed Case(s) - Official Quarantine
Equine Herpesvirus- Respiratory
May 03, 2021
Hampshire County, MA
Information Only